Ultrasonic delay line glass

ABSTRACT

AN ULTRASONIC SOLID DELAY LINE GLASS HAVING THE COMPOSITION, IN MOLE PERCENT, CONSISTING OF SIO2 54 TO 65%; B2O3 17 TO 28%; SIO2+B2O3 79 TO 85%; AL2O3 3 TO 6%; R2O 3 TO 10%; AND PBO 6 TO 13%, AND HAVING A LOW TEMPERATURE COEFFICIENT OF DELAY TIME AT ABOUT ORDINARY TEMPERATURE, IN WHICH SAID R2O MAY BE SUBSTITUTED BY AT LEAST ONE METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF CAO AND MGO, SUCH THAT THE COMPOSITION STILL CONTAINS 3% R2O AND IN WHICH SAID PBO MAY BE SUBSTITUTED BY AT LEAST ONE METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF BI2O3, ZRO2 AND BAO, IN AN AMOUNT OF 0 TO 8%, 0 TO 4% AND 0 TO 6%, SUCH THAT THE COMPOSITION STILL CONTAINS 5% PBO, AND R REPRESENTS AT LEAST ONE ALKALI METAL IS DISCLOSED.

Mlmh 26, l974 sYozo TAKEucHl ULTRASONIC DELAY LINE GLASS Filed Aug. 14, 1972 HUI Si 02 B203 IIIIIIII TEMPERATURE PatenteaMar. 26, .1974y 3,799,784 Y, ULTRASONIC DELAY LINE GLASS v Syozo Takeuchi, Kanagawa, Japan, assignor to Fuji Photo Film Co., Ltd., Kanagawa, Japan Continuation-impart of abandoned application Ser. No.`

867,381, Nov; 2, Ser. No. 280,299

Claims priority, application Japan, Oct. 31, 1969,

4/87,347 -V Int. Cl. C03c 3/08, 3/10, 3/30 U.S. Cl. 106-53 1970. This application Aug. 14, 1972,

2 Claims i ABSTRACT OF THE DISCLOSURE tains 3% R20 and in which said Pb0 may be substituted by at least one metal oxide selected from the group consisting of Bi203, Zr02 and BaO, in an amount of 0 to 8%, Oto 4% and 0 to 6%, such that the composition still contains 5% PbO, and R represents at least one alkali metal is disclosed.

CROSS REFERENCES TO RELATED* APPLICATIONS This application is a continuation-in-part application of copending application Ser. No. 86,381, led Nov. 2, 1970, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a glass composition used as an ultrasonic delay line.` More particularly, the present invention relates to a boric acid-silica glass used as an ultrasonic delay lline for radar, color television, video devices and the like.

DESCRIPTIONVOF THE PRIOR ART Ultrasonic solid delay lines have 'recently been em ployed for radar, color television, video devices and the like. As materials for these ultrasonic solid delay media, there have been hitherto used 'quartz glass, alkali-leadsilica glass and the like (see, for example, U.S. Pat. 3,154,425). However, an alkali-lead-silica glass has poor melting properties, andl hence it has been diicult to produce. The glass according to the present invention consists of a composition which is different from these known glasses and is practically useful as an ultrasonic delay line.

The variation in delay time with temperature of an ultrasonic delay time must be small, and thus, for example, in a PAL color television system, a time variation of only within i5 nano-seconds with a temperature United States Patent Oice' variation of from v10 to 40 C. is permissible with respect to a delay time of 63.9 ,aseo corresponding to 1H- (i.e., the Yscanning time Brown tube).

An object of the present invention is to provide a novel glass having good characteristics for ultrasonic delay lines.

per oneY horizontal line on a TV- Another object of this invention is to provide a novel i I I :.2:- conditions and one which has useful values of energy loss and frequency properties.

These and other objects of this invention will become` apparent from an examination of claims which follow. i

SUMMARY OF VTHE INVENTION they specification` and of Si02 54 to 65%; B203 17 to 28%; Si02-l-B2O2 7 9 to A1203 3 to 6%; R20 3 to 10%; and PbO 6 to 13%, hand having a low temperature coeiiicient of delay time at about ordinary temperatures, in which said R20 may be substituted by at least one metal oxide selected from the group consisting of CaO and MgO, such that the cornposition still contains 3% R20 and in which said PbO may be substituted by at least onev metal oxide selectedfrom the group consisting of Bi202, Zr02 and BaO, in an amount of Oto 8%, Oto 4%. and Oto 6%, such that the land R represents at composition still contains 5% PbO, least one alkali metal.

"BRIEF DESCRIPTION oF THE AccOM1 .\NYING-f DRAWINGS FIG. 1 shows the relationship between (SiO2-l-B2O2) content and the variation in delay time with the change in temperature.

FIG. 2 shows the variation in delay time with the change in temperature.

DESCRIPTION 0F THE PREFERRED EMBODIMENTS the delay line must be within the range of i3. The glasses shown in FIG. 1 considerably differ from each other in composition. The numerals in FIG. 1 show the mol percent yof Pb0 (partly including Bi203, BaO and Zr02). It

can be understood from FIG. l lthat theb sumJ ofy the ('Si02-i-B20'2) content greatly inuences the' rvalue of the v. T.C.D., and that, where the sum of the (Si02-{-B2O2) content is the same, the T.C.D. changes in the negative direction with an increase in the amount of PbO.

In glasses practically used as a delay line, the temperature variation of the delay vtime often has `aminimum value as lshown in FIG. 2. FIG. 2 shows the delay time variation (AT), on the basis of 20 C., of delay line'ha-ving a central frequency of 4.433619 mHz. and a delay time (T) of 63.943 itsec.

In vexample A of FIG. 2, the variation in the delayA In YExample B of the 2, thevariation in the delay time T.C.D., was calculated as follows.

The total quantity of glass-forming oxide; i.e., Si02 and B203 is substantially related to the temperature c0- efcient. Thus, if the sum (SiO2-l-B2O3) is not within the above-mentioned value, the temperature coefficient of the Iglass becomes large. The optimum total quantity of Si02 and B203 may be inuenced by the kinds of other glassmodifying loxides and, inv general, the larger theiluantity ofafP-bO, the-smaller thetotal quantity of- Si02 and B203m necessary, the addition of less than l weight percent such lining agents as As203 yandv Sb203 "may alsol bev becomes, and on the contrary, the larger the quantity permissible. of alkali oxide, R20, the larger the optimum total quantity The resulting glasses are transparent. Therefore, any of SiO2 and B2O3-becomes. 5 interior defects in the glasses such as foams and cords can If the total quantity is within the foregoing range, the be discovered with the naked eye. However, the addition respective amounts of Si02 and B203 may properly be of coloring agents such as C0304, Mn304, etc. thereto will varied within the stated limits. decrease the transparency, and it` will become dilicult to Consequently, the aforesaid limits are determined in observe the interior defects of the glasses. Accordingly, view of the majoriconsiderations of melting, formability l the addition of such coloring agents should be avoided so and the chemical durability of the glass. as to obtain an ultrasonic delay line without any interior `It is,`of` course, natural that of the proportion of Si02 defects. to B203 is-War'ied, the ultrasonic property of the glass may The glass of the present invention can be produced in alsQ be somewhat varied, accordance with a conventional process, `for example, as The addition of A1203 prevents the phase separation of l shown in U.S. Pat. No. 3,154,425- For example, tbe glass SiO2 and B203 and the proper amount thereof is 3 6 mole composition is melted lat about 1400 C.l and fired with percent'- l suicient stirring so as to form neither bubbles nor cord. The alkali oxide, R20, is also added to lower the melt- The melting Carl usually be carried out ina pot furnace ing temperature of the glass. In a case where the content but a tank fllrnaee may be Used i0 Conduct tbe melting of SiO2 and B203 and the content of 'A1203 are within the 20 and forming Of the glass continuously. foregoing ranges, if the balance is R20, it is possible to The forming iS generally Carried out in any olle of'lbe forma glass delay medium having a desirable temperature known glaSS fOrmng processes such as a casting processv coefficient but in general, the ultrasonic wave loss in the for a large Sire block, a Continuons roll ProeeSS, a PreSS glass becomes larger lwith'the increase of the R20 content. ProeeSS and ille like (See, for eXarnPle, the GlaSS Therefore, it is desirable to control the proportion of Engineering Handbook by E- B Shand, Published by R20 to such an extents@ as to satisfy the necessity of McGraw-Hill BOOk C0mpany A Chunk glass according lowering the melting point of the glass and introduce Pb0 lo a large Size bloek caS'fing ProCeSeor Continuous rOll instead, process is made into the desired shape by cutting, pressing The PbO influences the propagated velocity and the and grindingultrasonic wave loss; that is, if the quantity of PbO is in- The glass material formed S then subjected l[0 annealcreased, the propagated velocity is lowered and the diing by a method Wbiell iS Conventional for an optical mensions of the delay line are reduced, thereby making glaSS- More Specifically, the glaSS material iS heated t0 the the ultrasonic Wave loss l0w annealing temperature or to a temperature slightly higher A part of the Pb0 may also be replaced with oxides (l-e by 20 C-30 C-) than ille annealing temperature of heavy metals Such as Blzoa, Zr02 and BaO, Such that 35 and maintained at that temperature until any strain is rethe composition still contain 5% PbO, but the replacemoved Le fol' at least 5 hours, Usually 24.hours. The ment of Pb() with Ba() makes the ultrasonic loss highl glass, thereafter, is cooled at a rate not higher than 5 However, replacement of a part of l[he Pb() with either 1/hr., and it is preferable, to obtain lgood results, to con- Bizoa, Zr()2 or BaO is not advantageous, In Ordinary tinue the coolingV to a temperature as low as possible. manufacturing, since replacement of the PbO with BaO Thus, for eXalnPle, die cooling Caribe Continued to a temmakes the ultrasonic loss high, only up to 6 mole percent Pefatul'e of about 209 C- to Secure eXeelleIl effeets. of the pbo can .be replaced with Baa In addition, The present invention will be illustrated in greater dealthough the chemical durability is improved to some extall by reference lo the following non-limiting eXalnPleS- tent since the replacement of the PbO with Zr02 results EXAMPLES in a glass composition which is diicult to melt, only up to 4 mole percent of the Pb0 can be replaced with Zr0'2. A square glass bar (12 X 12 X 180 mml Was obtained Further, even though a relatively large amount of Bi203 as follows; can be added to the composition,v because no undesirable Each of the glass composltons Shown ln Table 1 below deterioration results, since Bi203 is expensive, only up to was heated up to about 14,00 C- to be melted in a Plant' about 8 molepercent of the Pb0 should be replaced with 50 mun? furnace and successively the melt was Sublected to Bi203. Replacement with an excess amount of Bi2O3 .may Casting. T he casted block was cut. and ground to form cause corrosion of the Platinum pot used for melting the same intc: a bar. The thus-obtained bar was reheated and hence it is not very advantageous from an'industrial to about 500 C' for anneahngolurposes and the bal' Was standpoint. Furthermore, it is possible to replace a part of then' cgoled at the rate of 5"3 C/hf m11 lt Was oooled the R20 with Cao', Mgo, .veta However, although 1.e 55 to 200 C., and thereafter allowed to cool naturally 1n furplacing the R20 with Cao and Mg() does not deleteri nace. Ultrasonic transducers (lead-zirconate-titanate, shear ously influence the delay line properties of the glass, it Wave mode: 4 mHZ- l0 Inm- X 5 1 11111.) Were attached to renders the melting of the glass difficult and therefore both ends of the bar by epoxy resin adhesive, and meas- 3 mole percent of R20 must be present in the glass comurements 0f varlOuS physical properties were performed. position. Replacement of R20 with CaO or MgO im- 60 Table 1 ShOWsvthe Compositions of the various glass bars proves the chemical durability to some extent. If tested as well as the results of those tests.

. 3 TABLE 1 Example si at at, el at a i9 ai :it ai 83 8l32 8'10 82:2 85:3 82 8i 8i 8i f 2.5 2.9 3.o 4.2 1.6 4 3 12.5 9.o 3 5 2 6 2 4.5 4.8 5.0 8.4 3.6 s 5 12.5 15.8 4 5.2 6.2 4 3.9 3.o 3.4 3.o 2 2 3 3 2.0 3.5 s 7.7 9.5 6.5 9.0 5 10 5.5 s 10.0 8.6

1.4 2 e L5 .4 v 1.6 "n: Lss'. db "lsl iig lit l? 1312 2'12 "8102i +55@ -lgg ill-g elle Velocity of sound mJsec 2, 960 2, 990 2.910 2,900 2, 930 2,880 3,110 2,960 3,270 3, 730 3,010 2,970 2.930

l Temperature coefficient o! delay (time).

The loss (ultrasonic) shown in the table is an apparent value including losses by transducers and adhesive on both ends.

The glass composition in the table is given in molar percent, and the thermal change of delay time represented by T.C.D. shows an average temperature variation of C. 60 C. as p.p.m./ C.

Examples 1 to 6 are in accordance with the present invention While 7 to 13 are comparative examples. In these Examples 1 to 6, the SiOz-l-B203 is within the range of this invention.

Examples 1 and 2 show the results achieved when a portion of the PbO is replaced with BaO and Zr02 and a part of the PbO is replaced with BaO, respectively.

In IExamples 12 and 13, although the temperature coeicient of the delay time is good, when the Si02 content is as large and the B303 content is as small as in these examples, the melting property of the glasses are so poor that they are dicult to produce.

Example 10 shows the case in which the PbO content is 0. In such a case, the temperature coeicient of the delay time is not very good. In addition, the loss becomes large due to the large content of R30, and the wave velocity also becomes great due to the absence of PbO. Since the form of the delay line will become large with the increase in wave velocity, this is disadvantageous.

Additionally, although the glass described in U.S. Pat. NO. Contains Sloz, A1203, B203, alkaline oxide, C0304, Mn304, alkaline earth oxide and Ti03, as is apparent from the examples described therein, these SiOz-l-B203 contents convert, in mol percent, to 69.43%, 77.02% and 72.68%, respectively. It will be clear from the above-described comparative examples that it is impossible to use the glass composition containing abovestated amount of Si03-l-B303 as a glass for ultrasonic delay lines.

What is claimed is:

1. An ultrasonic solid delay line glass having a temperature coefficient of delay time within the range of about -0.3 106 to l-0.3 108 and having the composition, in mole percent, consisting of Si02 54 to 65%; B203 17 to 28%; SiOz-l-B203 79 to 85%; A1203 3 to 6%; R20 3 to 10%; and PbO 6 to 13%, and having a low temperature coetlicient of delay time at about ordinary temperatures, in which said R30 may be substituted by at least one metal oxide selected from the group consisting of CaO and MgO, such that the composition still contains 3% R20 and in which said PbO may be substituted by at least one metal oxide selected from the group consisting of Bi303, ZrOZ and BaO, in an amount of 0 to 8%, O to 4% and 0 to 6%, respectively, such that the composition still contains 5% PbO, and R represents at least one alkali metal.

2. The glass composition of claim 1 wherein ning agents of As203 or Sb303 are added to the composition in an amount of less than 1 weight percent, based on the weight of said composition.

References Cited UNITED STATES PATENTS 2,525,536 10/1950 Faatz et al 106-53 2,949,376 8/ 1960 Comer 106-53 3,258,351 -6/1966 Paymal 106--53 3,475,704 10/ 1969 Van Der Burgt S33-30 R FOREIGN PATENTS 417,297 1947 Italy 106-53 ALLEN B. CURTIS, Primary Examiner M. L. BELL, Assistant Examiner U.S. Cl. X.R. 106-54 'i l 

